Merge pull request SCons#4445 from jcbrill/jbrill-gh4320-fix

Fix 4320: add an optional argument list string to the configure CheckFunc method

Author: bdbaddog

CHANGES.txt

@@ -13,6 +13,11 @@ RELEASE  VERSION/DATE TO BE FILLED IN LATER
     - Use of NotImplemented instead of NotImplementedError for special methods
       of _ListVariable class
 
+  From Joseph Brill:
+    - Fix issue #4320: add an optional argument list string to configure's CheckFunc
+      method so that the generated function argument list matches the function's
+      prototype when including a header file.
+      
   From William Deegan:
     - Fix sphinx config to handle SCons versions with post such as: 4.6.0.post1
 

RELEASE.txt

@@ -26,8 +26,9 @@ DEPRECATED FUNCTIONALITY
 CHANGED/ENHANCED EXISTING FUNCTIONALITY
 ---------------------------------------
 
-- List modifications to existing features, where the previous behavior
-  wouldn't actually be considered a bug
+- Add an optional argument list string to configure's CheckFunc method so
+  that the generated function argument list matches the function's
+  prototype when including a header file. Fixes GH Issue #4320
 
 FIXES
 -----

SCons/Conftest.py

@@ -231,17 +231,22 @@ def _check_empty_program(context, comp, text, language, use_shared: bool = False
         return context.CompileProg(text, suffix)
 
 
-def CheckFunc(context, function_name, header = None, language = None):
+def CheckFunc(context, function_name, header = None, language = None, funcargs = None):
     """
     Configure check for a function "function_name".
     "language" should be "C" or "C++" and is used to select the compiler.
     Default is "C".
     Optional "header" can be defined to define a function prototype, include a
     header file or anything else that comes before main().
+    Optional "funcargs" can be defined to define an argument list for the
+    generated function invocation.
     Sets HAVE_function_name in context.havedict according to the result.
     Note that this uses the current value of compiler and linker flags, make
     sure $CFLAGS, $CPPFLAGS and $LIBS are set correctly.
     Returns an empty string for success, an error message for failure.
+
+    .. versionchanged:: 4.7.0
+       The ``funcargs`` parameter was added.
     """
 
     # Remarks from autoconf:
@@ -274,6 +279,9 @@ def CheckFunc(context, function_name, header = None, language = None):
         context.Display("Cannot check for %s(): %s\n" % (function_name, msg))
         return msg
 
+    if not funcargs:
+        funcargs = ''
+
     text = """
 %(include)s
 #include <assert.h>
@@ -287,14 +295,15 @@ def CheckFunc(context, function_name, header = None, language = None):
 #if defined (__stub_%(name)s) || defined (__stub___%(name)s)
   #error "%(name)s has a GNU stub, cannot check"
 #else
-  %(name)s();
+  %(name)s(%(args)s);
 #endif
 
   return 0;
 }
 """ % { 'name': function_name,
         'include': includetext,
-        'hdr': header }
+        'hdr': header,
+        'args': funcargs}
 
     context.Display("Checking for %s function %s()... " % (lang, function_name))
     ret = context.BuildProg(text, suffix)

SCons/SConf.py

@@ -1002,8 +1002,8 @@ def SConf(*args, **kw):
         return SCons.Util.Null()
 
 
-def CheckFunc(context, function_name, header = None, language = None) -> bool:
-    res = SCons.Conftest.CheckFunc(context, function_name, header = header, language = language)
+def CheckFunc(context, function_name, header = None, language = None, funcargs = None) -> bool:
+    res = SCons.Conftest.CheckFunc(context, function_name, header = header, language = language, funcargs = funcargs)
     context.did_show_result = 1
     return not res
 

SCons/SConfTests.py

@@ -671,11 +671,26 @@ def test_CheckFunc(self) -> None:
                                  log_file=self.test.workpath('config.log'))
 
         try:
-            # CheckFunc()
+            # look for function using default heading
             r = sconf.CheckFunc('strcpy')
             assert r, "did not find strcpy"
+            # no default heading, supply dummy signature
             r = sconf.CheckFunc('strcpy', '/* header */ char strcpy();')
             assert r, "did not find strcpy"
+            # ... supply complete signature, and function args
+            r = sconf.CheckFunc('strcpy', header='/* header */ char *strcpy(char *dest, char *src);', funcargs='"", ""')
+            # ... supply standard header for prototype, and function args
+            assert r, "did not find strcpy"
+            r = sconf.CheckFunc('strcpy', header='#include <string.h>', funcargs='"", ""')
+            # also try in C++ mode
+            cpp_header = """\
+#ifdef __cplusplus
+extern "C"
+#endif
+char *strcpy(char *dest, char *src);
+"""
+            r = sconf.CheckFunc('strcpy', header=cpp_header, funcargs='"", ""', language="C++")
+            assert r, "did not find strcpy"
             r = sconf.CheckFunc('hopefullynofunction')
             assert not r, "unexpectedly found hopefullynofunction"
 

doc/man/scons.xml

@@ -3954,7 +3954,7 @@ Returns a boolean indicating success or failure.</para>
   </varlistentry>
 
   <varlistentry>
-  <term><replaceable>context</replaceable>.<methodname>CheckFunc</methodname>(<parameter>function_name, [header, language]</parameter>)</term>
+  <term><replaceable>context</replaceable>.<methodname>CheckFunc</methodname>(<parameter>function_name, [header, language, funcargs]</parameter>)</term>
   <listitem>
 <para>Checks if <parameter>function_name</parameter> is usable
 in the context's local environment, using the compiler
@@ -3982,17 +3982,18 @@ char function_name(void);
 </programlisting>
 
 <para>
-Note: if <parameter>header</parameter> is supplied,
-it should <emphasis>not</emphasis>
-include the standard header file that declares
-<parameter>function_name</parameter>,
-and it <emphasis>should</emphasis> include a
-dummy prototype similar to the default case.
-Compilers reject builds where a function call does
-not match the declared prototype as happens
-if the "real" header is included,
-and modern compilers are now rejecting
-implicit function declarations.
+If <parameter>header</parameter> is supplied, it should <emphasis>not</emphasis> include
+the standard header file that declares <parameter>function_name</parameter> and it
+<emphasis>should</emphasis> include a dummy prototype similar to the default case.  If
+this is not possible, the optional <parameter>funcargs</parameter> argument can be used
+to specify a string containing an argument list with the same number and type of
+arguments as the prototype.  The arguments can simply be constant values of the correct
+type.  Modern C/C++ compilers reject implicit function declarations and may also reject
+function calls whose arguments are not type compatible with the prototype.
+</para>
+
+<para>
+<emphasis>Changed in version 4.7.0: added the <parameter>funcargs</parameter>.</emphasis>
 </para>
 
 <para>Returns a boolean indicating success or failure.</para>

test/Configure/config-h.py

@@ -41,7 +41,7 @@
 import os
 env.AppendENVPath('PATH', os.environ['PATH'])
 conf = Configure(env, config_h = 'config.h')
-r1 = conf.CheckFunc('printf')
+r1 = conf.CheckFunc('printf', header='#include <stdio.h>', funcargs='""')
 r2 = conf.CheckFunc('noFunctionCall')
 r3 = conf.CheckFunc('memmove')
 r4 = conf.CheckType('int')